sext.h

Sign-extend halfword

Sign-extends the least-significant halfword in the source to XLEN by copying the most-significant bit in the halfword (i.e., bit 15) to all of the more-significant bits.

Assembly format

sext.h rd, rs1

Decode Variables

Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];

Execution

  • IDL

  • Sail

if (implemented?(ExtensionName::B) && (misa.B == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
if (xlen() == 32) {
  X[rd] = {{16{X[rs1][15]}}, X[rs1][15:0]};
} else if (xlen() == 64) {
  X[rd] = {{48{X[rs1][15]}}, X[rs1][15:0]};
}
{
  let rs1_val = X(rs1);
  let result : xlenbits = match op {
    RISCV_SEXTB => sign_extend(rs1_val[7..0]),
    RISCV_SEXTH => sign_extend(rs1_val[15..0]),
    RISCV_ZEXTH => zero_extend(rs1_val[15..0])
  };
  X(rd) = result;
  RETIRE_SUCCESS
}

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction

Encoding

svg

Defining extension

  • Zbb, version >= Zbb@1.0.0

Access

M HS U VS VU

Always

Always

Always

Always

Always

Containing profiles

  • Mandatory: RVA22S64, RVA22U64, RVA23M64, RVA23S64, RVA23U64, RVB23M64, RVB23S64, RVB23U64

  • Optional: